Patas Monkey (Erythrocebus patas) Fact Sheet: Reproduction & Development

Mating period brief

• c. 10 weeks (Chism and Rogers 1997)

Soliciting partners

• Female crouches in front of male and exhales into her cheek pouches (Mittermeier et al. 2013)
  • Male more likely to initiate copulations when multiple males are with the group (Carlson and Isbell 2001)
    • Twice as likely, one study (Carlson and Isbell 2001)
• Occurs at times other than the breeding season (Isbell 2013)

Copulation

• Typically early in the day; morning (Chism and Rogers 1997; Mittermeier et al. 2013)
• Interrupted frequently by juveniles; harass male (Carlson and Isbell 2001)
  • Male harassed in 64-74% of observed copulations
• No forced copulation reported (Carlson and Isbell 2001)

Number of mating partners

• Females: 1-2, typically (Carlson and Isbell 2001)
  • Even when numerous extra-group males join a group
• Males: 2-5, typically (Carlson and Isbell 2001)

No overt, physical signs of reproductive cycle; except menstruation (Hall 1966)

• Unlike baboons and mangabeys, which show sexual swellings and color changes

High reproductive rate (Isbell et al. 2009)

• Yearly reproduction common (Chism et al. 1984; Isbell et al. 2009; Isbell et al. 2011; Nakagawa et al. 2003)
• Females typically reproduce annually through most of their lives (Isbell et al. 2009)
  • 79% of group females reproduce each year, one study in Kenya (Isbell et al. 2009)

Conception during the wet season, summer (Mittermeier et al. 2013)

• Introduced population in Puerto Rico also follows a pattern of mating during the wet season and giving birth in the drier season (Gonzáles-Martínez 2004)

No paternal care of offspring, father does not directly assist in care of his offspring (Chism and Rogers 1997)

• Many fathers no longer with group when offspring are born, one study (Chism and Rogers 1997)

Gestation

• c. 23.8 weeks or 5.5 months, reports from managed care populations (Isbell 2013; Mittermeier et al. 2013; Whittaker et al. 2014)
• Late in pregnancy the female's nose changes color, from black to white; in all but the eastern patas subspecies (Mittermeier et al. 2013)
  • Reverts to black c. 45 days after birth (Mittermeier et al. 2013)

Seasonal birth

• In dry season; c. 2-4 months long depending on location (Nakagawa et al. 2003)
  • Late December to mid-February; West African patas in northern Cameroon (Nakagawa et al. 2003)
  • November to February; eastern patas and two other populations of western patas (Nakagawa et al. 2003)

Diurnal birth, give birth in daylight (Isbell 2013; Isbell et al. 2009; Mittermeier et al. 2013)

• Unlike most other monkeys (Isbell 2013; Isbell et al. 2009; Mittermeier et al. 2013)
• Labor and delivery short (Mittermeier et al. 2013)
  • < 1 hr (Mittermeier et al. 2013)
• 1 infant, typically (Isbell 2013)
  • Birth weight: c. 504 g (c. 1 lb) (Harvey et al. 1987)
  • Coat dark brown or black (Mittermeier et al. 2013)
• Adult females often attempt to take babies from their mothers (Isbell 2013)
  • Viewed as allomothering by some (Muroyama 1994)

Interbirth interval

• c. 12 months; range 12-14 (Isbell et al. 2009; Nakagawa et al. 2003)
• Among the shortest of all cercopithecines, including the baboons, macaques, and vervet monkeys (Butynski 1988; Cheney et al. 1986)

Infant (< 1 yr old)

• Appearance
  • Dark brown or black coat, first 3 months (Hall 1966)
  • Face pink
  • Sexes similar, unable to determine sex unless in close proximity (Isbell 2013)
• Maternal Care
  • Infants cling to mothers' bellies; heads directed forward (Hall 1966; Mittermeier et al. 2013)
    • Carried up to 7 months of age; only in emergencies past this age (Isbell 2013)
    • By 3 months of age, begin to closely follow mother during search for food (Hall 1966)
  • Weaned 3-5 months (Isbell 2013; Nakagawa 2000)
    • Begin solid food c. 3 months (Hall 1966)
    • Rapidly shift from dependence on milk to independent foraging (Nakagawa 2000)
• Annual mortality rate
  • 26% of infants do not survive their first year (Isbell et al. 2009)
  • Causes of death
    • Predation, most significant cause of death (Isbell et al. 2009)
    • Infanticide and kidnapping, or death of mother (Isbell et al. 2009)
      • Infants from other groups are sometimes taken during inter-group encounters (Chism 1999b; Isbell 2013; Nakagawa 1995)
  • Infants orphaned after 6 months of age can survive (Isbell et al. 2009)

Subadult

• Males
  • Scrotum assumes pale blue color c. 3 yrs (Isbell 2013; Rogers and Chism 2009)
  • Disperse from natal group, c.3 yrs of age; range 2.5-4.5 yrs (Isbell 2013; Isbell et al. 2009; Nakagawa et al. 2003; Rogers and Chism 2009)
    • Prior to descent of testes, typically (Isbell 2013; Nakagawa et al. 2003)
    • Likely to avoid aggression with the adult male (Rogers and Chism 2009)
  • Live alone or in shifting all-male groups until reaching adulthood (Chism and Rogers 1997; Nakagawa et al. 2003)
• Females
  • Vulva turns pink c. 2 yrs of age (Isbell 2013)

Adult

• Males
  • Mature c. 5 yrs (Chism et al. 1984)
  • Group leaders stand watch much of the time (Hall 1966)
    • Remain apart from group, often several 100 m (Hall 1966)
    • Survey area for intruding males, often from a high point (Hall 1966; Isbell personal communication)
• Females
  • Age at first reproduction c.3 yrs (Chism et al. 1984; Isbell et al. 2009; Isbell et al. 2011; Nakagawa et al. 2003)
    • Earliest of all cercopithecines; rarely do others (vervets) reproduce as young (Chism et al. 1984; Isbell personal communication)

Wild populations

• 4.7 years, on average (Isbell et al. 2009)

Managed care

• Median life expectancy
  • 15.1 years (AZA 2023)

Annual mortality rates

• Adults: c. 4%-47% (Isbell et al. 2003; Nakagawa et al. 2003)
• Juveniles: c. 13%-27% (Nakagawa et al. 2003)
• Infant and adult female mortality rates often similar over the long term (Isbell et al. 2009)
  • Greatest causes of adult mortality likely predation and illness (Isbell et al. 2009)
  • Drought associated with higher mortality rates, one west African study (Nakagawa et al. 2003)

Predation

• Black-backed jackal (Canis mesomelas) and domestic dog (Canis familiaris) are the only confirmed predators (Isbell 2013)
• Likely and potential threats (from Enstam and Isbell 2002; Isbell 2013; Isbell et al. 2009 unless otherwise noted)
  • Canids
    • African wild dog (Lycaon pictus), domestic dog (Canis familiaris), black-backed jackal (Canis mesomelas)
  • Felids
    • Lion (Panthera leo), African wild cat (Felis sylvestris), leopard (Panthera pardus), serval (Felis serval), caracal (Felis caracal), cheetah (Acinonyx jubatus)
  • Hyaenids
    • Spotted hyena (Crocuta crocuta)
  • Birds
    • Martial Eagle (Polemaetus bellicosus)
  • Other primates
    • Olive baboon (Papio anubis); potentially prey on immature patas (Enstam and Isbell 2002)
    • Robust chimpanzee (Pan troglodytes), West Africa only

Parasites

• Intestinal nematodes; 5 species reported (McGrew et al. 1989b)
• Flatworms
  • Cestodes, eg. Taeniid cysticerci (Sulaiman et al. 1986)
  • Trematodes, eg. Schistosoma mansoni (Kuntz et al. 1977)
• Entamoeba and Iodamoeba protozoans (McGrew et al. 1989b)

Disease

• Epidemic illness can spread through populations, killing many (Isbell et al. 2009)
  • May reduce or prevent reproduction
  • Death results either directly from disease, decreased resilience to parasitic infection, or from an increased likelihood of predation
  • One unidentified illness associated with weakened and stiffened hind limbs, weight loss, lethargy, apparent confusion, and (in some) cataracts and bleeding in the eyes (Isbell et al. 2009)
• Simian immunodeficiency virus (SIV) (from Isbell 2013 unless otherwise noted)

Accidental death

• Puff adder (Bitis arietans) observed killing, but not eating patas (Isbell 2013)

Male group leader on watch.

Male group leaders often sit apart from females, on a high perch to watch for intruding males.

Image credit: © Bethany Weeks from Flickr. Some rights reserved.

Butynski (1988)

Carlson and Isbell (2001)

Cheney et al. (1986)

Chism (1999b)

Chism and Rogers (1997)

Chism et al. (1984)

Enstam and Isbell (2002)

Gonzáles-Martínez (2004)

Hall (1966)

Harvey et al. (1987)

Isbell (2013)

Isbell et al. (2009)

Isbell et al. (2011)

Kuntz et al. (1977)

McGrew et al. (1989b)

Mittermeier et al. (2013)

Muroyama (1994)

Nakagawa (1995)

Nakagawa (2000)

Nakagawa et al. (2003)

Rogers and Chism (2009)

Sulaiman et al. (1986)

Whittaker et al. (2014)